What is Extrinsic Evidence?

Legal Definition
Evidence that relates to a contract, but is not contained within the document itself (for example, circumstances surrounding the negotiations of the contract). This evidence is not admissible unless there is an ambiguity in the contract. See: parol evidence rule.
Legal Definition
External evidence, or that which is not contained in the body of an agreement, contract, and the like.

2. It is a general rule that extrinsic evidence cannot be admitted to contradict, explain, vary or change the terms of a contract or of a will, except in a latent ambiguity, or to rebut a resulting trust. 14 John. 1; 1 Day, R. 8; 6 Conn. 270.
-- Bouviers Law Dictionary
Legal Definition
evidence that does not appear in a contract or written document but has a bearing on an issue.
Legal Definition
Proof not contained in the document itself, offered to explain or modify its contents.
-- Ballentine's Law Dictionary